In some electronic devices, as for example in switched-mode DC/DC converters, there is a valley inductance current which can become negative. This negative valley inductance current results in an inefficient power consumption. Therefore, to maintain the efficiency of the stand-by mode of the electronic device, which should be a low power consuming mode, this waste of energy, caused by the valley inductance current becoming negative, should be avoided. To achieve that, the valley inductance current polarity change should be detected as soon as possible, especially when this polarity goes from positive to negative. Therefore, some detectors of valley inductance current polarity change in a switched mode power supply (SMPS) circuit charged with an inductive charge have been developed.
It is known in the art, as described in more detail with respect to FIG. 1, to provide such a detector of valley inductance current polarity change in a pulse width modulated circuit charged with an inductive charge. The implementation of FIG. 1 presents a first drawback of being based on a very accurate comparator which is complex and expensive. A second drawback concerns performance degradation in some working modes and a need for some non-negligible static power consumption. This second drawback can be addressed, but at the cost of complicated design and calibration techniques, which in turn make the detector still more complex and expensive.
Therefore, prior art detectors either cannot provide an accurate detection of valley inductance current polarity change, or can provide for an acceptable detection of valley inductance current polarity change in terms of accuracy, but at the cost of a complex and expensive detection device.